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Early Jurassic Dinosaurs
The dinosaurs of the Early Jurassic were still fairly similar to those from the end of the Triassic Period. When we see little outward change in the appearance of a group of animals over a long period of time, we say that they have a conservative body plan. This is the case with most of the early dinosaurs. There was not a lot of variation in the habitats around Pangea, so there was little need for radical physical adaptation.
The earliest Jurassic dinosaur that has been discovered was described in 2016. It was found in the same cliffs of southern England that yielded remains of the flying reptile Dimorphodon.
Dracoraptor was a small predator that probably hunted along the shore, feeding on small lizards and possibly insects, but it may also have taken on more challenging prey on occasion.
Prosauropods from the Early Jurassic don’t look very different from prosauropods of the late Triassic, even though, by this time they were quite common and had developed a cosmopolitan distribution. At 14 feet long, Massospondylus was a medium-sized prosauropod that was smaller and more lightly built than its ancestor Plateosaurus, but it still had its awkward, front-heavy look.
Lesothosaurus was one of the most primitive of all ornithischians—the bird-hipped dinosaurs. Just over three feet long, Lesothosaurus was a small bipedal herbivore. It had long legs for its size and was probably a fast, athletic animal.
Remains of Massospondylus and Lesothosaurus have been found in South Africa, where they lived amid an environment of meandering streams and rivers.
Dilophosaurus
By the early Jurassic, the theropods had arrived at an elegant but powerful body plan that would continue to be perfected over the next 150 million years. Dilophosaurus was a 23-foot-long carnivore and one of the largest predators of its time. It was distinguished by a pair of tall, thin crests at the front of its skull. Unlike the fictional depiction of Dilophosaurus in Jurassic Park, it did not have an expandable neck frill, and it probably wasn’t venomous. It was also much larger than the animal shown in the movie.
Dinosaurs in Antarctica?!
Today we know Antarctica as a frozen continent, but in the Early Jurassic it was still connected to Gondwana, the southern half of the supercontinent Pangea, and it was located much farther north than it is now. Back then, Antarctica was subtropical and supported a huge variety of life. So far, there have been very few dinosaurs found in Antarctica, but that’s not because they didn’t live there. It’s because the present-day conditions are so harsh and the rocks are buried under so much snow and ice that it’s very difficult to locate fossils, let alone excavate them.
Nonetheless, scientists have found some dinosaur fossils in Antarctica. Without question, the most famous is Cryolophosaurus, which was about 21 feet long and weighed around 1,000 pounds. Along with Dilophosaurus, it was one of the largest meat-eating dinosaurs of its time. And like Dilophosaurus, Cryolophosaurus sported an elaborate crest, but in this case, it stretched across its forehead between its eyes. The name Cryolophosaurus means “frozen crested lizard.”
